This invention relates to a counter reset to zero by a push button and adapted to be incorporated into a tape recorder and similar machine.
A tape recorder is usually provided with a counter reset to zero by a push button for the purpose of displaying the amount of run of the tape, or the recording time or the like. Such counter generally comprises a plurality of digit wheels each having a heart shaped cam, a plurality of pinions each interposed between adjacent digit wheels for transmitting or carrying the rotation of a digit wheels of a lower order to a digit wheel of a higher order, a reset push button, a zero resetting bracket provided with a plurality of heart shaped cam depressing members operated by the push button to depress the heart shaped cam members for simultaneously resetting the digit wheels to zero, a pulley connected to the source of drive of the tape recorder through a belt or the like, a rotary shaft having one end supporting the pulley and the other end provided with a worm, a worm wheel meshing with the worm, a motion transmitting pinion meshing with the gear of the digit wheel of the first order, and a gear meshing with the pinion. These component elements are assembled on a U shaped frame.
The counter reset to zero by the push button further comprises means mounted on the frame for determining the distances between the digit wheel shafts and the pinion shafts for the purpose of establishing a proper meshing relationship between the digit wheels, gears, carry pinions, and the motion transmitting pinion; pinion aligning means for resiliently holding and aligning the carry pinions and motion transmitting pinions which are freed when reset; a spacer interposed between the digit wheel of the first order and its driving gear for preventing the transmission of motion by friction between the gear and the digit wheel of the first order even when the counter is reset to zero during the operation of the tape recorder; and a stop member for preventing dropping off of the push button. As disclosed, for example, in Japanese Utility Model Publication No. 9642 of 1969 dated Apr. 18, 1969, of the tytle "Zero Reset Mechanism of a Zero Resettable Counter" the frame of an early stage push button zero reset counter was made of metal. However, a frame prepared by press working a metal plate is impossible to have various functions described above. For this reason, a large number of component parts are required which of course requires troublesome assembling steps. With the advance in material and metal mold manufacturing techniques, the frame of the counter has been molded from synthetic resinous materials. For example, Japanese Utility Model Publication No. 15089 of 1971 dated May 26, 1971 of the title "The Frame of the Push Button Type Zero Reset Counter" discloses a frame molded from a synthetic resinous material and intergrally formed with a groove for mounting a push button and stop member. Even with such molded frame, the difficulties described above are not eliminated completely. U.S. Pat. No. 3,777,973 dated Dec. 11, 1973 discloses a molded frame integrally formed with pinion aligning resilient members. Japanese Utility Model Publication No. 5070/72, dated Feb. 22, 1977 discloses an improved spacer which prevents frictional transmission of power between the digit wheel of the first order and its driving gear. U.S. Pat. No. 3,337,129 dated Aug. 22, 1967 discloses an improved assembly of a plurality of digit wheels and pinions. However, the techniques discloses in these prior references can not be applied to the counters of the push button zero resetting type. Thus, although these prior art devices were developed to solve independent problems they are not directed to radically improve the construction of the counter so as to obtain an ideal counter resettable with a push button and having a high degree of reliability that can be manufactured at a low cost.
In U.S. Pat. No. 3,627,228 assigned to the same assignee as the instant application there is disclosed a tape position marking and sensing device in which a tape recorder control signal is produced while a digit wheel of the highest order rotates from 0 to 9. However, the counter disclosed therein is not of the push button zero reset type. The construction of the digit wheels including the digit wheel of the highest order of this counter may be the same as that of the push button zero reset type so that it would be efficient if a signal producing means could be readily incorporated into this push button zero resetting type counter.